The present invention relates generally to surgical instruments, and more particularly to surgical instruments useful for stabilizing a portion of a beating heart during coronary surgery.
Surgeries to treat heart disease, and particularly narrowing and/or blockages in the coronary arteries that supply oxygen and nutrients to the heart, are increasing in numbers due to the aging of the population in America and other developed nations, as well as the diets in such nations and a variety of other factors. Classical open heart surgery techniques have been performed to bypass coronary artery blockages, often by rerouting the blood flow around the blockage, using a graft, such as from the saphenous vein. Another technique involves supplying blood to a location downstream of a blockage by anastomosing another artery to the coronary artery, e.g. a mammary artery.
These techniques have traditionally been performed only after stopping the beating of the heart, and connecting the patient""s circulatory system to a heart-lung bypass machine, which supplies the patient with the needed circulatory and oxygenation functions while the heart is stopped and the surgeries are being performed. All during this process, blood flow into the chambers of the heart is bypassed. Various post-procedure side effects have been associated with the use of the bypass machine, some of which can be severe. For example, the mechanical damage to the blood tissues that results from the pumping action of the bypass machine has been associated with increased risks of postoperative embolisms and stroke. To alleviate the increased postoperative risks associated with bypass surgery, beating heart surgeries are becoming increasingly prevalent, in which the heart beat is not stopped, but maintains the circulatory flow of blood, oxygen and nutrients throughout the surgery. A bypass machine is not used.
Methods and apparatus for performing a coronary artery bypass graft (CABG) procedure on the beating hear are described in U.S. Pat. Nos. 5,894,843 and 5,727,569 to Benetti et al., the entireties of which are herein incorporated by reference thereto. In a typical CABG procedure, a blocked or restricted portion of a coronary artery, which normally supplies blood to some portion of the heart, is bypassed using a source vessel or a graft vessel to re-establish blood flow to the artery downstream of the blockage or restriction. This procedure requires a surgeon to create a fluid connection, or anastomosis, between the source or graft vessel and an arteriotomy or incision in the coronary artery. The formation of an anastomosis between two such vessels is a particularly delicate procedure, which requires precise placement of sutures in the tissue surrounding the arteriotomy and the source or graft vessel. An anastomosis between vessels of these dimensions is tedious during a stopped-heart procedure, but during a beating heart procedure it is markedly even more difficult.
As could be expected, it is very important that the target site for the anastomosis be stabilized to remain substantially motionless, even while the remainder of the heart tissue remains beating all around the target site. To this end, a number of devices have been developed which are directed to stabilizing a target site on the beating heart for the purpose of completing a cardiac surgical procedure, such as completing an anastomosis. Representative devices useful for stabilizing a beating heart are described, for example, in U.S. Pat. Nos. 5,894,843; 5,727,569; 5,836,311 and 5,865,730.
As beating heart procedures have evolved, new challenges have arisen in the design and engineering of the stabilization devices. The heart is typically accessed by way of a surgical incision such as a sternotomy or a thoracotomy. Such an incision, even with the use of one or more retractors leaves only a limited opening space within which to perform the surgical procedures. Often one ore more of the blocked or restricted arteries are located a good distance away from the access incision, requiring the stabilization device to traverse a longer and more tortuous path than if the artery were located so as to be directly exposed to the access incision. Also, distant locations can be such that the stabilization device must engage the surface of the heart at difficult angular relationships or orientations. Under the most severe conditions, devices which operate to provide a mechanical force to stabilize the beating heart can encounter difficulty maintaining mechanical traction against the surface of the heart if they are not sufficiently maneuverable, and devices which utilize suction or vacuum to engage the heart can have a difficult time maintaining a vacuum seal against the heart tissue for the same reason.
Even a device that is extremely maneuverable so as to be able to place the stabilizing portion of the device at many locations on the heart may not have a sufficiently small size of low profile to be an effective device. Since the working space provided by the incision opening is quite limited, it is desirable to make the stabilization device as small and low profile as possible to maintain maximum working space, as well as visibility for the surgeon.
In view of the foregoing, it would be desirable to have methods and devices for stabilizing the beating heart that improve upon the maneuverability of the existing devices while maintaining or decreasing the amount of space that is occupied thereby, to provide the surgeon with more working space, better visibility and to make the overall procedure easier by making the operation of the stabilization device easier and more effective.
The present invention will be primarily described for use in stabilizing the beating heart during a surgical procedure, but the invention is not limited thereto, and may be used in other surgical procedures. Described herein is a stabilization system including a tissue contact member having a surface adapted to contact the tissue and temporarily maintain the tissue in a relatively immobilized state; and a maneuverable arm attached to the tissue contact member, which includes at least one articulating joint formed by a link having a male articulating surface composed of angled teeth and a female articulating surface having angled trenches adapted to receive the angled teeth. This type of articulating joint moves in one degree of freedom directed by the angled teeth sliding against the angled trenches.
In an example described, the maneuverable arm comprises a plurality of the above-described articulating joints. Further, one or more rotational joints may be provided, each formed by a link having a male articulating surface and a link having a female articulating surface, which are positioned for relative rotation in a plane perpendicular to a longitudinal axis of the maneuverable arm. The rotational joints, together with the articulating joints impart maneuverability in three dimensions to the maneuverable arm.
In an example described, a first rotational joint is provided intermediate the articulating joints and a second rotational joint is positioned at or near a proximal end of the maneuverable arm.
A low profile mount is provided which is connected at a proximal end portion of the maneuverable arm. The mount includes a first mount portion and a second mount portion, which is pivotally connected to the first mount portion. The first mount portion may be integral with a male or female articulating surface of a rotational joint that it then forms a part of at the proximal end of the maneuverable arm. The second mount portion is pivotal away from the first mount portion to position the mount over a fixed object, or to release the mount from the fixed object. The mount portion also allows the stablization system to be slid along a rail on a fixed object to which it is mounted. The second mount portion is pivotable toward the first mount portion to fix the mount on the fixed object.
The mount may further comprise a locking mechanism adapted to lock the second mount portion to the first mount portion in a closed position upon pivoting the second mount portion toward the first mount portion. The closed position is configured to lock the mount on the fixed object. The fixed object may be a sternal retractor, for example, or other object, which is stationary relative to the moving tissue. The mount portions may each further include a rail grip adapted to engage one side of a rail on a sternal retractor. The locking mechanism may include a living hinge formed in one of the first and second mount portions and a pin extending transversely on the other of the first and second mount portions, the pin being adapted to snap fit into the living hinge.
A cable passes internally through each of the articulating joints, rotational joints and mount of the device. The cable is further attached to a tensioning mechanism proximally of the mount. The tensioning mechanism may include a screw mechanism and a knob. The screw mechanism has a first threaded component having a first set of threads and a second threaded component having a second set of threads adapted to mate with the first set of threads. The first threaded component is fixed to the cable and the knob is adapted to torque the second threaded component with respect to the first threaded component. The screw mechanism is adapted to lock the first and second mount portions together in the closed position, to securely lock the stabilization system on the rail on which it is mounted.
The second threaded component may include a torque limiter having a unidirectional slip clutch, which is engageable with the knob. The knob positively engages the torque limiter for unthreading the second set of threads from the first set of threads, and positively engages the torque limiter for threading the second set of threads on the first set of threads until a predetermined amount of torque is required to further tension the cable. Upon reaching the predetermined amount of torque during threading, the torque limiter slips with respect to the knob.
The slip clutch may include at least one fin extending from an outer surface of the second threaded member at an angle to a line normal to a tangent line passing through the location from which the fin extends. Each fin is adapted to engage a groove formed in an inner surface of the knob.
The cable includes a stop member fixed to a distal end thereof, such that, upon applying tension to the cable with the tensioning member, the stop member and the tensioning member apply a compressive force to the articulating joints and rotational joints, thereby locking every joint into an assumed orientation.
A coupling mechanism which links the stop member to the tissue contact member, thereby also linking the maneuverable arm to the tissue contact member, is further provided. The coupling member is adapted to lock the tissue contact member in an assumed position when the cable is placed under a sufficient tension to lock the maneuverable arm.
The coupling mechanism may include a ball member fixed to the tissue contact member and a socket member rotatably joined with the stop member and adapted to receive the ball member to form a ball joint. The socket member may further include a slot through a side wall thereof, which terminates in an enlarged opening dimensioned to permit the ball member to pass therethrough. The coupling mechanism may further include a coupling link having arms adapted to lock with the socket member, and an upper abutment surface adapted to abut the stop member. A second coupling link having driving surfaces adapted to contact a distal most link of a distal most articulating joint of the maneuverable arm may also be provided. The second coupling link further includes a lower abutment surface adapted to abut an upper portion of the ball member, wherein, upon tensioning of the cable, the stop member draws the first coupling link and the socket member in a proximal direction, whereby the socket member compresses the ball member against the lower abutment surface.
Optionally, a flexible sleeve positioned over the articulating joints and the rotational joints of the maneuverable arm. The flexible sleeve may comprise an elastomer, such as silicone or dip molded PVC, for example. Preferably, the flexible sleeve comprises a material having a four or six way stretch, such as LYCRA(copyright), or SPANDEX (elastomeric fabric of fibers containing polyurethane), for example.
The tissue contact member is rotatable in three degrees of freedom with respect to the distal end of the maneuverable arm. The tissue contact member may be locked with respect to the maneuverable arm in virtually any position to which the tissue contact member may be maneuvered when in an unlocked state. The locking mechanism simultaneously locks the maneuverable arm in virtually any position to which the maneuverable arm may be maneuvered when in an unlocked state.
The tissue contact member may include a pair of feet extending substantially parallel to one another and adapted to straddle a target site on the tissue. The pair of feet may extend from a common base portion and the common base portion may be angled away from a plane in which the feet substantially extend. Other tissue contact members described herein may be incorporated into the system as described herein. A large variety of tissue contact members may be adapted for use in the stabilizer of the present invention by providing each with a ball member extending therefrom which is adapted to form a ball joint at the distal end of the maneuverable arm.
Tissue contact members which employ negative pressure to aid in the stabilizing function may also be utilized, in one example, each contact member or foot of the tissue contact member includes a thin compliant seal extending around a perimeter of a bottom surface thereof. Each compliant seal may have a tapering thickness, wherein the thickness is greater adjacent the bottom surface of the foot and tapers thinner in a direction extending away from the bottom surface. The compliant seal may have a tapering length, forming a variable seal, wherein the length measures a distance that the seal extends away from the bottom surface. The seal may have a greater length near the proximal end of the foot than near the distal end of the foot. The tissue contact members, whether employing negative pressure or not are substantially rigid, as described herein, although malleable contact members may also be employed.
In one example of a tissue contact member that employs negative pressure, the tissue contact member includes a manifold base interconnected with a pair of feet. The manifold base is substantially hollow and has a pair of fittings extending therefrom, on which the feet are mounted. Each foot is independently rotatable about the respective fitting, with respect to the manifold base. Each foot has a hollow interior defining a vacuum chamber, with each vacuum chamber having a first opening adapted to engage at least a portion of the tissue and a second opening fluidly coupled with an opening through the respective fitting extending from the manifold base.
Each vacuum chamber may further include channels formed on an upper interior surface of the foot. The channels may be aligned substantially parallel to one another and extend in a direction from the proximal end to the distal end of the foot. A deep channel may be formed near the distal end of each foot, to fluidly communicate with the opening through the respective fitting.
Each foot may have an asymmetrical transverse cross-section. A porous filter may be provided to cover at least a portion of the channels in each vacuum chamber. The porous filter may be integrally molded with the thin compliant seal on each foot. Each seal may be provided with one or more grooves to further enhance the flexibility thereof.
A rotatable fitting may be mounted to the manifold base, thereby providing a rotational connection between a vacuum line and the manifold base adapted to snap fit over said third fitting, said rotatable fitting further comprising an inlet tube configured for connecting with a vacuum line, whereby the vacuum line is rotatably mounted to said manifold base.
Other novel tissue contact members are also described herein, including one having a pair of feet comprising an extremely low profile structural member and a thin compliant seal extending from a bottom perimeter of the structural member.
A tensioning mechanism for applying tension to a cable passing through a maneuverable surgical instrument is described as comprising a screw mechanism and a knob. Alternatively, a one-step lock mechanism may be employed that uses a coarser thread, or camming surfaces to lock/unlock the mechanism with a single partial turn. The screw mechanism has a first threaded component having a first set of threads and a second threaded component having a second set of threads adapted to mate with the first set of threads. The first threaded is fixed to the cable and the knob is adapted to torque the second threaded component with respect to the first threaded component.
The second threaded component may include a torque limiter, which may include a unidirectional slip clutch engaging that engages the knob up to a predetermined torque level and then slips with respect thereto, thereafter.
A device for providing additional stabilization to tissue already in contact with a primary stabilization member is disclosed which includes at least one tissue contact member adapted to be placed on the tissue in an area bounded by primary tissue contact members, and a connecting member extending from the at least one tissue contact member and adapted to be hand held or fixed to a relatively immovable object. The device is also included with a primary stabilization device in a stabilization system.
A method of stabilizing tissue at a location of a target site at which an operative procedure is to be performed is described to include contacting the tissue in the vicinity of the location with a primary stabilizing instrument to stabilize the general vicinity of the location; and contacting the tissue in a location between the location where the primary stabilizing instrument contacts the tissue and the target site, to further stabilize the target site.
The method may further include fixing each of the primary and second stabilizing instrument to the same or different relatively immovable objects after tissue contact has been established. The secondary stabilizing instrument may alternatively be fixed to the primary stabilizing instrument or hand held.
These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the instruments and methods as more fully described below.